Conventionally, a CMOS image sensor (hereinafter, abbreviated as CIS) has been a rolling shutter system in which an exposure timing of each pixel is shifted by each row. In the case of the rolling shutter system, focal plane distortion occurs when an object moving at high speed is imaged. Thus, a global shutter system which can unify exposure timings of all the pixels has been developed.
The CIS adopting the global shutter system has the structure in which signal charges from a photodiode (PD) which performs photoelectric conversion according to incident light are transferred to a floating diffusion (FD) as a charge holding unit, and the FD holds the transferred signal charges until the next readout period.
However, if intense light is incident on the PD during the period when the FD holds the signal charges, a charge (hereinafter, also referred to as a noise charge) generated by stray light (PLS) corresponding to the incident light amount is mixed in the FD and superimposed as a noise component on the held signal charges. As a result, noise is included in a pixel signal so that the image quality of the obtained image is considerably deteriorated.
Thereupon, as a mechanism for subtracting the noise charges from charges (signal charges+noise charges) read out from the FD, there has been proposed an invention in which a noise charge capacitance is provided in each pixel circuit (e.g., see Patent Document 1).